From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 28FB9C35FFC for ; Tue, 25 Mar 2025 13:30:59 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 431F6280017; Tue, 25 Mar 2025 09:30:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3920F28000C; Tue, 25 Mar 2025 09:30:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 20B3E280017; Tue, 25 Mar 2025 09:30:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id EDD3A28000C for ; Tue, 25 Mar 2025 09:30:57 -0400 (EDT) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id C31A91604D8 for ; Tue, 25 Mar 2025 13:30:57 +0000 (UTC) X-FDA: 83260158954.03.9DB1B35 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf30.hostedemail.com (Postfix) with ESMTP id 99FDD80007 for ; Tue, 25 Mar 2025 13:30:52 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=nz9sujFM; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf30.hostedemail.com: domain of brauner@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=brauner@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1742909452; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=DaWN0XNM3I3mhlPJsgKB+kMMvzQDyTJ+FA4uddm9Kow=; b=pDMbTtPRQYOpygFdyq57JzF03pfTcchjRR/zNKgYMfuN9nURdcBMROA3LPt6koG+8b+SzC wBkpNJZBTVMkfBjviU/yIA5E6BNQoMPB3FGag0IbFLiPab7Ye8DukzxCJ7utoJ0d16TDgB +0JWf+R3uT6sfE+fyEPJSACkViq6wjA= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=nz9sujFM; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf30.hostedemail.com: domain of brauner@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=brauner@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1742909452; a=rsa-sha256; cv=none; b=OGnsEaeUxSO5cXVrWmc8Xn0U6hFVpOWRvQMNNxHISboP+/PcNXgpVO00YtBjM3gMFAuCcg d3Ar2JkCrJFujjBV1y7QamcxfUV/kpr8vVyJUA0d40MnfXUzcNNW4Ej8yoxwEemh0NBpAI i+9vb/zRkCPCWsTRix91q8pub7F52Kg= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 0A99B5C42B6; Tue, 25 Mar 2025 13:28:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B5527C4CEE4; Tue, 25 Mar 2025 13:30:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1742909450; bh=AFz+xR3cxeybdFAR0wl1Pa8igU585gpjH4/Of2Jdma8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=nz9sujFM3jGlX1cHt1JguczqA9ISu3qQOHeNcNTi0xtlHx3RtUm8YOKu+XOdXSJYD p6EVnBJ3EdnHncBhfmMt9LJMgvNLuku6QMo79r8+amEoMRiqXpXBS6mgSIoWwNxbFP hmbg+j0B5rDfafyIFtDp8pWDMx7U9BEODq8Ql+KV/XkNapaHROK2GS/mteMQ/+o26p BthSbV2ScCG5HtKovdxiRSkTtYQ+U3/hZ0n/zTMLqAlbXrjq1Pwj9bxrcicKOiXpYg mMSfuXBDJoUoBj9zQPHGbNEOmnbhQi4muH9u9dxgy5932q46Mm3N0W652+cJWdsVhL J27Sgbv+cdCqA== Date: Tue, 25 Mar 2025 14:30:48 +0100 From: Christian Brauner To: Oleg Nesterov , Mateusz Guzik Cc: syzbot , kees@kernel.org, viro@zeniv.linux.org.uk, jack@suse.cz, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com Subject: Re: [PATCH] exec: fix the racy usage of fs_struct->in_exec Message-ID: <20250325-bretter-anfahren-39ee9eedf048@brauner> References: <67dc67f0.050a0220.25ae54.001f.GAE@google.com> <20250324160003.GA8878@redhat.com> <20250324182722.GA29185@redhat.com> <20250325100936.GC29185@redhat.com> <20250325132136.GB7904@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250325132136.GB7904@redhat.com> X-Rspamd-Server: rspam01 X-Stat-Signature: rgb8my6zr3azqrta8aep8csfoekc7xjm X-Rspam-User: X-Rspamd-Queue-Id: 99FDD80007 X-HE-Tag: 1742909452-553455 X-HE-Meta: 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 QE14VEBe dDHulr+616sVkFqdkm8aFB1xCOYU3hrF0RX3leIDPQg475qnkYjdMi/pm9BB5aDTyyRJk+cjJBqsJLdnosq2ewpmmz+EabHEPWObBlqGY+GNa5qeTYL01ekZ/quaUKGw1zxP+IInRluE0P56NMFg+XJ5NiZB4Y0HG+agf20TSjm506ui9pAoCWDbsZ7fHFQRGBr0QcnrETUN1eRiLqfz9kiFcy9CpRCxo6WpDSq6db/sqD/OEHgoDzXne5NnKUdt1Jb/LtgoGbwfrUvseNvCgINZC5yMA+4z4/tttJXBetMwE6l+vn0hA58lXdCJXYBU4vK3Aj+QDldE6ilVZGqyN1HQgpkkoN23sIk8yrIqpz9R1rHYlfTYlEDmXDvkV1CvCW5Nq6CVLznXiIBSD/e3FfjbreUuGCJKxSe3nZshZpwQLcze2l43jIzR3Dc3OAh45kSPGQbCX6ztOq75P8WaVcpd14XH8bMFbFOQje4PHC3A79Og= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000052, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Mar 25, 2025 at 02:21:36PM +0100, Oleg Nesterov wrote: > On 03/25, Mateusz Guzik wrote: > > > > On Tue, Mar 25, 2025 at 11:10 AM Oleg Nesterov wrote: > > > > > > On 03/24, Mateusz Guzik wrote: > > > > > > > > On Mon, Mar 24, 2025 at 7:28 PM Oleg Nesterov wrote: > > > > > > > > > > So to me it would be better to have the trivial fix for stable, > > > > > exactly because it is trivially backportable. Then cleanup/simplify > > > > > this logic on top of it. > > > > > > > > So I got myself a crap testcase with a CLONE_FS'ed task which can > > > > execve and sanity-checked that suid is indeed not honored as expected. > > > > > > So you mean my patch can't fix the problem? > > > > No, I think the patch works. > > > > I am saying the current scheme is avoidably hard to reason about. > > Ah, OK, thanks. Then I still think it makes more sense to do the > cleanups you propose on top of this fix. I agree. We should go with Oleg's fix that in the old scheme and use that. And then @Mateusz your cleanup should please go on top!